Feverfew

Feverfew was used by Greek physicians to treat “melancholy,” which may have included headaches as well as depression.

The English used it into the seventeeth century for symptoms that might translate today into vertigo, depression, and headache, as well as for lowering fever. It faded from popularity after that, and during the eighteenth and nineteenth centuries was hardly used by herbalists.

It was, however, planted in gardens, perhaps for the small daisylike flowers or because it had a reputation for repelling insects. If that didn’t work, it was sometimes used as a balm to ease the itching of insect bites.

In many places it escaped from the garden and now grows as a wildflower in much of the northeastern United States. Only in recent decades has it come back into regular use, primarily to prevent migraine headaches.

Dried leaves and stems, picked while the plant is flowering (July through October), are the parts used.

Active Ingredients

The principal measured component of feverfew is parthenolide, one of several sesquiterpene lactones.

Canadian regulations call for a minimum of 0.2 percent parthenolide in feverfew products, while the French pharmacopoeia specifies a minimum of 0.1 percent. Parthenolide levels vary greatly, but most leaves from feverfew grown in North America contain less than 0.1 percent.

In addition, feverfew contains flavonoid glycosides, particularly apigenin and luteolin. Melatonin has also been reported as a component of feverfew leaves.

How much of the activity of feverfew is due to parthenolide (which is also found in a number of other plants) and how much should be attributed to other compounds has not been determined.

Uses

Feverfew has been studied and found effective for the prevention of migraine headaches, reducing the number of headaches suffered by as much as 70 percent, or reducing the pain and controlling the nausea commonly experienced with such headaches.

Once a migraine headache begins, however, feverfew does not appear to relieve the pain.

A recent review has found that much of the research to determine the effectiveness of feverfew for this purpose was of questionable quality. It does appear likely, however, that the herb has some benefit.

Three trials, at least two of them double-blind, have demonstrated efficacy of the whole leaf. Health and Welfare Canada has approved a standardized feverfew product called Tanacet as a nonprescription drug for migraine prophylaxis.

Feverfew has been linked to several measurable changes in physiology. Extracts of the aboveground parts of the plant can reduce the body’s manufacture of prostaglandin, a chemical important in inflammation, by up to 88 percent.

This and other anti-inflammatory activity might explain why the herb has been used to treat psoriasis. Despite this, a clinical trial for rheumatoid arthritis showed no benefit over placebo.

In the test tube, feverfew extracts can keep blood platelets from sticking together and forming clots, so the herb may be useful as a mild anticoagulant. It achieves this through a different chemical pathway than aspirin or other salicylates.

Feverfew also blocks platelets from releasing serotonin, which may help to explain how it works to prevent migraines.

Feverfew extracts also prevent the release of histamine from mast cells, so the plant may be useful in the treatment of allergies. Presumably, it is also expected to lower fever, although there don’t appear to be modern clinical studies substantiating this traditional use.

Dose

For the prevention of migraines: chew two to three fresh leaves daily; or take 125 mg of dried herb with 0.2 percent parthenolide. Treatment for at least two months is recommended.

Dose’s from 50 to 200 mg of dried herb have been used for other indications but recommendations vary widely.

Special Precautions

Feverfew may slow blood clotting, so it is prudent to avoid this herb in the period just prior to and following surgery.

Feverfew is not recommended for pregnant women. In folk medicine it has the reputation for initiating menses.

Women should also refrain from taking feverfew while they are breast feeding, and it is not appropriate for children under two years of age.

Feverfew belongs to the family of asters. Anyone allergic to ragweed or other flowers in the family should probably avoid use of this herb as a sensible precaution.

Adverse Effects

The most common side effect of feverfew appears to be the development of mouth ulcers (canker sores). Approximately 11 percent of the patients treated in one study reported this problem.

A smaller proportion of people chewing fresh leaves of the plant have experienced inflammation of the mouth and tongue, swelling of the lips, and loss of the sense of taste.

Gastrointestinal side effects such as indigestion or flatulence have been reported occasionally but appear to be mild in most cases. More troublesome is a reported increase in heart rate in a few individuals.

People who handle feverfew may develop a skin reaction on exposure (contact dermatitis).

Treatment with feverfew should not be discontinued suddenly. One study with a crossover design documented a rebound syndrome with severe migraines, sleep disturbances, anxiety, and joint stiffness when patients were switched to placebo after having been on feverfew. Gradual dose reduction is advised.

Possible Interactions

Clinical cases of hemorrhage have not been described, but in theory feverfew could increase the risk of bleeding in people taking anticoagulants such as Coumadin, aspirin, Plavix, or Ticlid.

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About the Author

Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.” Read Joe's Full Bio.